s7 1200 Math: ADD

Hi!

When I have signal at my IN on the ADD block constantly add IN1+IN2. How do I do to just get one calcutation when I have IN signal? I guess I can take a pulse on 1ms and use it to trigger it? But is there a standard solution?

You want to trigger your ADD instruction with a 'one-shot', or as Siemens calls it, a 'transition detector'. These turn ON for only one scan, so your ADD instruction will only fire once each time your signal occurs.

See section 6.1.1.2 (page 91) of this manual.

http://www.sea.siemens.com/us/inter...tomation/DOCS2/S7-1200_System_Manual_enUS.pdf



-Eric

Thanks alot, will try this! P_Trig it is =)